Oil light on & off, although oil level ok

[fourcircle]

This is an odd one. My oil light came on a couple of weeks ago and even though I thought the oil level should be fine I figured I was wrong, so I checked the oil level. It seemed ok but perhaps a fraction low so I topped it up a bit, everything seemed ok, and then later on it came on again. So now it's coming on for a few seconds and then disappearing. It seems fairly random, although it has come on when cornering hard sometimes and it has also come on when driving straight at 30mph.
Now the oil level is sitting at the upper limit, where I would normally want it to be sitting. I can't figure out why the warning keeps coming and going though.
Does anyone have any ideas? It's a 3.0 V6 ASN engine.
Cheers
nj

 

[S4_dan]

Are you sure it's not the oil pressure symbol rather than oil level symbol?
If it is oil level, maybe the sensor is playing up.

Have you plugged in VCDS to see what codes (if any) are stored?

 

[fourcircle]

That's a good point mate. I've never seen an oil pressure sensor warning before that I'm aware of. Erm... What does it look like?
I'm off to do a scan....

 

[mattmanwrx]

I wouldn't drive or even start the car if the pressure is low. Just found this image online, if it helps.

 

[fourcircle]

Thanks for that mate. That was a bit of a wake up call. I hadn't even considered it was oil pressure because the car was driving fine and it just comes on and then disappears again.
I scanned the car and got these:

17522 - Oxygen (Lambda) Sensor: B1 S2: Internal Resistance too High
16684 - Random/Multiple Cylinder Misfire Detected
16685 - Cylinder 1 Misfire Detected
16688 - Cylinder 4 Misfire Detected
16690 - Cylinder 6 Misfire Detected
16686 - Cylinder 2 Misfire Detected

I'm not sure they're actually connected because I don't recall any kind of misfire, unless maybe it happened while my wife was driving. She says not but may not have even noticed.

I had the oil changed a few weeks ago by a local garage when they were doing the handbrake cables (way too much of a pain in the *** to do the cables myself) and this is the first time in about 6 years that I've let anyone else change the oil. So now I need to go and find out exactly what oil they have used and maybe think about changing it again, taking off the sump and cleaning out whatever the hell I find in there. I've just scanned a few threads and found a lot of 1.8T owners who have had issues with oil pressure and had to clean out a mesh filter within the sump.

ahhhhhhh nuts....

 

[Sandra]

Thanks for that mate. That was a bit of a wake up call. I hadn't even considered it was oil pressure because the car was driving fine and it just comes on and then disappears again.
I scanned the car and got these:

17522 - Oxygen (Lambda) Sensor: B1 S2: Internal Resistance too High
16684 - Random/Multiple Cylinder Misfire Detected
16685 - Cylinder 1 Misfire Detected
16688 - Cylinder 4 Misfire Detected
16690 - Cylinder 6 Misfire Detected
16686 - Cylinder 2 Misfire Detected

I'm not sure they're actually connected because I don't recall any kind of misfire, unless maybe it happened while my wife was driving. She says not but may not have even noticed.

I had the oil changed a few weeks ago by a local garage when they were doing the handbrake cables (way too much of a pain in the *** to do the cables myself) and this is the first time in about 6 years that I've let anyone else change the oil. So now I need to go and find out exactly what oil they have used and maybe think about changing it again, taking off the sump and cleaning out whatever the hell I find in there. I've just scanned a few threads and found a lot of 1.8T owners who have had issues with oil pressure and had to clean out a mesh filter within the sump.

ahhhhhhh nuts....

For future reference.
http://www.audi-sport.net/xf/pages/dash_warning_lights/

 

[fourcircle]

perfect. thanks. now bookmarked. I'm doubting myself and hoping the light is amber, rather than red. I just can't remember. But I'm prepared now to get it garaged and start pulling it apart if needed. not happy but prepared at least.

 

[fourcircle]

sh*t. it's definitely the oil pressure. I cleared the codes this morning and the car was fine when I was driving about town. In the afternoon though when I was driving the light came on so I brought it home gently. I scanned for fault codes and there are none though, which is odd. I thought there would have been something. Anyway, I need to get it into a garage to test the pressure. Fingers crossed it's not an epic problem.

 

[fourcircle]

sooooo... the oil pressure warning light pretty much disappeared for a while and we were only doing very short trips around town (I may have been horsing about a bit in my 20v coupe). Back in mid February I called a trusted mechanic (rally driver who builds his own cars and repairs other people's so I trust he knows what he's talking about) and he said there's a very high chance it's just the sensor if it only pops up and then goes away again. With work and everything I kind of forgot about it but it made an appearance again a couple of days ago so I ordered a new oil pressure sensor from the local dealer and will fit it when it arrives any day now.
The question is, is the sensor located on the oil filter housing or is it elsewhere? Does anyone happen to know the location before I stick my head into the underside of the engine bay? I can't find specific info for the ASN online.
cheers

 

[mattmanwrx]

Have you seen this thread on audizine? Similar problem that the guy fixed... Seems it was a sludge problem.

http://www.audizine.com/forum/showt...-Oil-Pressure-Warning-Light-2002-3-0L-Quattro

 

[fourcircle]

No I hadn't seen that actually. Thanks matey. This actually fits now that I think about it. I did a couple of half hour drives and wondered why the light came on when I was nearing my destination. Could be that after cruising at a reasonable speed I then slow down and the drop in revs allows sediment to fall back where it's not supposed to be...
So "pan" is the sump pan then? So I'll need to drain the oil, remove the pan, check the screen/gauze and possibly clean it. I wonder what kind of sealant I need to use when putting it back on again? And about 7 litres of decent oil at Finnish prices. f*ck.
And why oh why did this happen the first time I asked a garage to change my oil?
I wish the guy had posted where the ****** sensor's located instead of just saying he found out. what kind of forum practice is that? I'm glad we don't all just post smugly that we found a solution to each problem and not share the info (rant, rant, rant......)
OK, i'll stop now.

 

[mattmanwrx]

I found the thread while searching for the sensor location. But does seem like it is what you're experiencing.

Yes, the pan is the sump. I'm not sure on the sealant.

I just did an oil change on my s4 - 9.2 liters of oil went it!! When I found out it took 9 liters I was shocked!!

Also you mention that it has happened after a garage changed the oil. Did you specify which oil to use? Maybe they used a thick oil and it isn't being picked up properly? Or the oil has been contaminated with something?

 

[fourcircle]

9 litres? holy sh1t!
The oil on the receipt was OK. I'll double check but i'm pretty sure it was 5W40 Mobil 1. Contamination is always possible, or it's possible that the filter was changed quickly without letting the old oil and crap properly empty. Looks like I should order a new sump gasket now. I'll report back on what I find.
cheers

 

[stevey83]

Another thread revival for you! Did you ever change the pressure sensor? Mines playing up but the location of it is not ideal!

 

[fourcircle]

I ended up taking off the sump and cleaning the oil pick up, changed the sensor too (you're right. not an ideal location). If I remember right I left the oil filter on because it was new, put everything back together again but the issue came back. So i drained the oil AGAIN (and kept it), changed the oil filter for a decent one and then put the oil back in. And all was ok. So it was either crap stuck in the filter, or a ****** filter.